Deep in a Bavarian forest, a black reconnaissance drone buzzes overhead, piloted by US soldiers hoping to put lessons learnt from the war in Ukraine into practice.

Cheaper and more plentiful than in the past, drones are changing the face of modern warfare, particularly in Ukraine.

Both Moscow and Kyiv use them for armed attacks as well as surveillance, making it hard for combatants to hide.

"It's a transparent battlefield. That's why in Ukraine you see troops deep down in bunkers or consistently moving," said Brigadier General Steve Carpenter, training with the army at a base in Hohenfels, in the southern German state of Bavaria.

"You stop, you die."

Army Chief of Staff General Randy George said the US military is changing as a result of what it sees in Ukraine and the way drone warfare is........

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